It doesn't generate any electrical energy above and beyond the load. On an older car without an idle speed selenoid, you can start flipping on electrical accessories and hear the load increase and idle speed decrease. As the electrical load is increased, the mechanical load increases.
If you short the alternator, you will kill the engine. But don't do that because alternators aren't rated for that much mechanical energy or electrical load.
sorry, forgot my /s tag (which is for wimps! =P) on my last post when i said to quit embarrassing yourself. but i was addressing something else you had said.
and yes, there is electrical loss. just as there is mechanical loss. Chrysler (i believe) has been tinkering with electrical recovery from when the alternator is spinning harder than it has to, yet has not yet slowed to where it needs to be, for instance, when you drop from pulling a high load to a lower load. If we could harness that energy in between, that would help efficiency.